//
// Created by wze-zero on 2024/9/14 014.
//
#include <iostream>

using namespace std;

int main() {
    int num, n = 1;
    long sum = 0;
    cin >> num;
    while (num > 0) {
        num - n >= 0 ? sum += n * n : sum += n * num;
        num -= n;
        n++;
    }
    cout << sum << endl;
    return 0;
}